Regulation of cell survival in the pregnant rat endometrium.

妊娠的识别和维持是涉及母体和胚胎信号的复杂过程。在啮齿动物着床早期，子宫内膜上皮细胞发生凋亡。随后，间质细胞经历蜕膜化，随后是蜕膜退行性变，涉及蜕膜细胞的凋亡。未能建立这样的沟通已被证明是哺乳动物不育的最重要原因。然而，调控子宫内膜细胞凋亡的分子机制尚未明确。有趣的是，我们的实验室已经证明了不同的转化生长因子-β亚型(转化生长因子-β1、转化生长因子-β2和转化生长因子-β3)在妊娠大鼠子宫中的表达是不同的：转化生长因子-β1和转化生长因子-β2存在于着床期和发育迟缓期，而转化生长因子-β3亚型仅存在于发育迟缓期。我们还提供了证据表明，不同的转化生长因子-β可以激活子宫内膜细胞中不同的信号通路。这强烈地表明，根据怀孕期间的情况，转化生长因子-β可以发挥重要作用，我们假设性类固醇孕酮和17b-雌二醇可能也参与了这一过程。该研究计划的总体和长期目标是检测和了解在妊娠的两个重要阶段：1)胚胎着床和2)DB回归期间，子宫内膜中转化生长因子-β亚型的表达以及内分泌、旁分泌和自分泌活性的调节。不同孕期、假孕和发情周期的大鼠子宫上皮细胞和间质细胞以及整个子宫将用于体内和体外研究。实验方法包括分子和生化技术，利用shRNA上调表达载体和下调关键蛋白，体内生化抑制信号通路，原位和通过流式细胞术和免疫荧光技术进行细胞凋亡。从这些研究中获得的信息将有助于理解转化生长因子-β亚型在这些关键生殖状况中的重要性，并将为成功建立和维持妊娠提供重要线索。

Recognition and maintenance of pregnancy are complex processes involving both maternal and embryonic signals. In the rodents during early implantation, endometrial epithelial cells undergo apoptosis. Later, the stromal cells undergo decidualization, which is followed by decidua basalis (DB) regression, involving apoptosis of decidual cells. The failure to establish such a communication has been shown to be the most important cause of infertility among mammals. However, the molecular mechanisms governing endometrial cell apoptosis are not yet defined. Interestingly, our laboratory has showed that individual TGF-b isoforms (TGF-b1, -b2 and -b3) are differently expressed in the uterus during rat pregnancy: TGF-b1 and TGF-b2 are present during implantation and DB regression, whereas TGF-b3 isoform is only present during DB regression. We have also provided evidence that distinct TGF-b can activate distinct signaling pathways in endometrial cells. This strongly suggests that TGF-b can play an important role depending of the situation during pregnancy and we hypothesize that sex steroids progesterone and 17b-estradiol, the hormones of pregnancy, might also be involved in this process. The overall and long term objective of the proposed research program is to examine and understand the regulation of expression as well as the endocrine, paracrine and autocrine activity of the TGF-b isoforms in the endometrium during the two important phases of pregnancy: 1) embryo implantation and 2) DB regression. Epithelial and stromal cells as well as whole rat uteri from different Days of pregnancy, pseudopregnat and estrous cycle will be used for in vivo and in vitro studies. Experimental approaches will include molecular and biochemical techniques, upregulation with expression vectors and down-regulation of key proteins using shRNA, biochemical in vivo inhibition of signaling pathways, apoptosis in situ and by flow cytometry and immunofluorescence. Information gained from these studies will help to understand the importance of TGF-b isoforms during these critical reproductive situations and will provide important clues for successful establishment and maintenance of pregnancy.